Twin-lattice atom interferometry

Abstract

Inertial sensors based on cold atoms have great potential for navigation, geodesy, or fundamental physics. Similar to the Sagnac effect, their sensitivity increases with the space-time area enclosed by the interferometer. Here, we introduce twin-lattice atom interferometry exploiting Bose-Einstein condensates of rubidium-87. Our method provides symmetric momentum transfer and large areas offering a perspective for future palm-sized sensor heads with sensitivities on par with present meter-scale Sagnac devices. Our theoretical model of the impact of beam splitters on the spatial coherence is highly instrumental for designing future sensors.

Multi-loop atomic Sagnac interferometry

“…The choice of symmetric beam splitting in our geometry suppresses phase noise of the beam splitting lasers, as well as the impact of spatially homogeneous AC-Stark and magnetic field shifts on the two arms of the interferometer 43 , 44 . We refer to dedicated studies for impacts of light shifts due to large momentum beam splitters 34 , 41 , 55 – 59 , and isolation or correlation methods to remove vibration noise 47 , 60 – 65 for quantum sensors which we expect to be exploited in a future experimental realisation of our concept.…”

“…Additionally, we have to consider constraints from the beam splitting process. The velocity acceptance of the beam splitter 41 , 43 may limit . Another constraint is to have the atoms within the central part of the beam splitter both at the start, limiting and , and at the last pulse for recombination, limiting and .…”

“…We assume for a typical experiment control system 31 , Earth’s gravity gradient , and rad/s using Earth’s rotation rate as an upper limit 50 , 51 . Limited by the velocity acceptance of the beam splitter 41 , 43 . Assuming a gravity gradient compensation 21 , 66 – 68 to , neglecting the impact on other terms as the small change in the enclosed area 66 .…”

“…Using molasses cooled atoms at microkelvin temperatures implies limits to the beam splitting efficiency 26 , 27 and consequently to the contrast of the interferometer in the rotation sensor 5 , 6 . Additional cooling steps such as evaporative cooling provide a mitigation strategy 26 , thus enabling atom interferometers with high contrast 28 – 30 , higher-order beam splitters as a route for enhancing their sensitivity 30 – 41 , 41 – 44 , and efficient launch mechanisms 28 , 29 , which our concept builds on.…”

“…1 ), atoms are coherently manipulated by two perpendicular light gratings (red and orange dashed lines) to form a multi-loop interferometer 23 . Pulsed light fields enable symmetric beam splitting of the atomic wave packets in the horizontal axis (red arrows) 41 , 43 – 45 and relaunching in vertical direction (orange arrows) 28 . This approach offers a variety of advantages: (i) the free-fall time can be tuned to scale the area, (ii) the area is well defined by velocities imprinted during the coherent atom-light interactions, and (iii) the geometry utilises a single axis for beam splitting which avoids the requirement for relative alignment 5 , 23 , 46 .…”